July 30, 2025

Mr. Ted O. Skinner, Jr.
President and CEO
Prestige Business Solutions, LLC
914 Arbor Forest Landing SW
Marietta, GA 30064

Dear Mr. Skinner:

Thank you for your letter to the Occupational Safety and Health Administration's (OSHA), Directorate of Enforcement Programs. You requested information on the requirements of OSHA's Occupational Noise Exposure standard (noise standard), 29 CFR § 1910.95. Specifically, you requested information on exposure to impulsive or impact noise exceeding 140 dB peak sound pressure level. This letter constitutes OSHA's interpretation only of the requirements herein and may not be applicable to any questions not delineated within your original correspondence. Your specific questions are paraphrased below, followed by OSHA's responses.

Question 1: What is OSHA's official position on enforcement of the 140 dB peak sound pressure level? Since the standard says, "should not exceed" rather than "shall not exceed," is the 140 dB level a recommendation or is compliance mandatory?

Response: Impulsive noise, which includes impact and impulse noise, is a rapid rise in sound pressure that typically lasts less than one second. Impulsive noise is generally more hazardous than continuous noise, and it has a synergistic effect when combined with continuous noise exposure. Some exposures can have peak levels above 170 decibels or dB (e.g., flash-bangs, large caliber firearms, breaching operations).

The footnote to Table G-16 of OSHA's noise standard states, "[e]xposure to impulsive or impact noise should not exceed 140 dB peak sound pressure level." The standard uses "should" instead of "shall" and therefore the 140 dB peak is not in itself an Action Limit (AL) or Permissible Exposure Limit (PEL). However, for several reasons, it has been OSHA's longstanding policy that occupational noise exposure exceeding 140 dB without protection poses a hazard that places workers at increased risk of being exposed above the PEL in a very short amount of time and consequently leads to extreme danger of suffering irreversible hearing loss.

The standard at 1910.95(d)(2)(i) states that all continuous, intermittent, and impulsive noise sound levels from 80 dB to 130 dB must be integrated into the measurement of noise¹ . Accordingly, for purposes of establishing a hearing conservation program, employers must include impulsive noise measurements of 80 dB to 130 dB when determining whether workers are exposed at or above the action level and required to be placed in a hearing conservation program. (See also response to question 3 below).

In addition, based on the noise standard's Appendix A calculations, in situations such as yours, when employee exposure to impulsive or impact noise exceeds the 140 dB peak sound pressure level, it is probable that exposure is at or above the action level within minutes, and the employee will need to be included in a hearing conservation program. Historically, OSHA's inspection data indicates that noise sampling for impact/impulse noise at many establishments within NAICS 713990, including shooting ranges, exceed the PEL. In many cases, the data also indicates that the severity was three times the PEL or more.

Preventing exposure to impact noise above 140 dB has long been recognized as an important practice in the occupational safety and health profession and in industry standards such as: The National Institute for Occupational Safety and Health (NIOSH)'s Health Hazard Evaluation Report 2013-0124-3208. This Report stated, "Impulsive noise is considered to be more damaging to hearing than continuous sounds [Dunn et al. 1991; Starck et al. 2003]. Unprotected exposure to high intensity impulsive noise can cause acute acoustic trauma, resulting in symptoms such as ringing in the ears (tinnitus) and temporary hearing impairment [Salmivalli 1967; Mrena et al. 2002]. Permanent hearing loss may also occur from exposure to high intensity impulsive sounds that exceed a critical sound pressure level by causing direct mechanical damage to the inner ear [Ward et al. 1961; Luz and Hodge 1971]."² In addition, the International Organization for Standardization in ISO 1999:2013, and the American National Standards Institute ANSI S3.44-1996 state that no exposure should be permitted above peak sound levels in excess of 140 dB [ECD 1986; ISO 1990; ANSI 1996].³

Several studies also support the high risk of hearing loss due to exposure to impact noise above 140 dB. Notably, an animal study concluded that short duration impulse noise is more damaging to the ear than continuous noise.⁴ These animal studies have shown that the most impulsive noise produced up to 20 dB greater permanent threshold shift at the high frequencies than did the Gaussian noise exposure. Similarly, an additional study stated that high-intensity impulse sounds will permanently damage delicate cochlear structures, and thus individuals who shoot firearms are at a higher risk of bilateral, high-frequency, noise-induced hearing loss (NIHL) than peer groups who do not shoot.⁵

Question 2: What weighting scale should be used to measure the peak sound pressure level (A, C, or Z) when using a noise dosimeter or sound level meter (SLM) on a gun manufacturer's indoor firing range?

Response: As noted in Question 1 above, the noise standard states "…140 dB peak sound pressure level," indicating that unweighted (dB, or Z-weighted, meaning no weighting) peak sound pressure should be utilized. OSHA uses the "true peak" reading on SLMs to measure this level.⁶ However, OSHA encourages employers to use specialized equipment to accurately measure peak impulses, such as encountered at firing ranges. For additional information, refer to the National Institute for Occupational Safety and Health (NIOSH), which continues to provide research and guidance in this area: https://blogs.cdc.gov/niosh-science-blog/2018/07/18/impulse-noise/

See also Noise and Lead Exposures at an Outdoor Firing Range- California, at www.cdc.gov/niosh/hhe/reports/pdfs/2011-0069-3140.pdf. This study shows peak sound level meter measurements greater than 160 dB and that some participants' TWA noise exposure exceeded the OSHA AL during gunfire and recommend noise controls that include the use of noise suppressors on firearms, limiting the number of daily gunfire exposures, the use of double hearing protection, and a hearing conservation program that meets the requirements of the OSHA Noise standard.

Question 3: What would OSHA look for when evaluating a gun manufacturer's indoor test firing ranges given that gunfire sound levels are inherently very high, some as high as 160 dBA or more?

Response: OSHA's Compliance Safety and Health Officers (CSHOs) evaluate each workplace on a case-by-case basis to determine whether the employer is in compliance with the applicable requirements of the noise standard, 29 CFR § 1910.95, available at: https://www.osha.gov/laws-regs/regulations/standardnumber/1910/1910.95

Additionally, section 1910.95(b)(1) of the noise standard provides that when employees are subjected to sound exceeding those listed in Table G-16, feasible engineering or administrative controls must be utilized, and if such controls fail to reduce exposure to acceptable levels, personal protective equipment must be provided and used. Paragraph (i)(1) goes on to provide that employers must make hearing protectors available to all employees exposed to an 8-hour TWA of 85 dBA or greater at no cost to the employees.

Please be aware that the current OSHA enforcement policy regarding 29 CFR § 1910.95(b)(1) allows employers to rely on only personal protective equipment and an effective hearing conservation program, rather than engineering and/or administrative controls, when hearing protectors will effectively attenuate the noise to which employees are exposed to acceptable levels. See, OSHA's Field Operations Manual, Section XI.B, Violations of Noise Standard.⁷

Further, NIOSH recommends the use of the most protective criterion (e.g., dual hearing protection) to limit the number of daily gunfire exposure. As you are aware, in situations such as weapons firing, where noise levels exceed 140 dB, single hearing protection may not be adequate. Therefore, under such circumstances, CSHOs will evaluate the use of a combination of abatement measures to determine whether a violation of the noise standard exists. For example, the use of double hearing protection, administrative controls and engineering controls. Please note that OSHA considers a 3dB to 5dB reduction to be a feasible engineering control. See, https://www.osha.gov/enforcement/directives/cpl-02-02-035.

Finally, since section 1910.95(d)(2)(i) of the noise standard provides that all continuous intermittent, and impulsive sound levels from 80 dB to 130 dB must be integrated into the measurement of noise exposure, CSHOs may conduct noise dosimetry monitoring which would include impulse noise, to determine whether an employer is in compliance with the noise standard. In the event of multiple impulse noise exposures throughout any day, a citation could be issued if there was insufficient PPE and or controls and if the total exposure measures above 85dBA, as an 8-hour time-weighted average (TWA)-the action level or a 90dBA TWA-the permissible exposure level.

Thank you for your interest in occupational safety and health. We hope you find this information helpful. OSHA's requirements are set by statute, standards, and regulations. Our letters of interpretation do not create new or additional requirements but rather explain these requirements and how they apply to particular circumstances. This letter constitutes OSHA's interpretation of the requirements discussed. From time to time, letters are affected when the Agency updates a standard, a legal decision impacts a standard, or changes in technology affect the interpretation.

To assure that you are using the correct information and guidance, please consult OSHA's website at http://www.osha.gov. If you have further questions, please feel free to contact the Office of Health Enforcement at (202) 693-2190.

Sincerely,

Erin P. Gilmore, Acting Director
Directorate of Enforcement Programs

¹ This range is due to the limitations of existing commercially available dosimeters at the time the standard was written, which will not accurately integrate peak noise levels greater than the maximum range of the instrument, typically 130-140 dB. (See 46 Federal Register 4137).

² https://www.cdc.gov/niosh/hhe/reports/pdfs/2013-0124-3208.pdf

³ https://www.cdc.gov/niosh/hhe/reports/pdfs/2013-0124-3208.pdf

⁴ Hamernik, R.P., Henderson, D., 1974. Impulse noise trauma. A study of histological susceptibility. Arch. Otolaryngol. 99 (2), 118e121.

⁵ https://pmc.ncbi.nlm.nih.gov/articles/PMC5634813/

⁶ https://www.osha.gov/otm/section-3-health-hazards/chapter-5#noiseeval

⁷ https://www.osha.gov/fom/chapter-4